I posted this problem a couple of days ago. I never found the cause and eventually got frustrated and uninstalled FSX and started over. Of course that sovled the problem.But here we go again, for no apparent reason this error msg"Flight Simulator was unable to load some programs files and will now exit. Please reinstall Flight Simulator to restore or repair the program installation." is back!!!I have not modified the sim so this makes not sense what so ever.I tried deleting the cfg file as Bill suggested but it does not work. I'm running the repair disk now to see what happens. Anyway this is weird soI hope that anyone having this problem will post. Maybe we can figure out whats causing it.System: Athlon fx-642gig ramgtx7800 vid600 gig hdxp professional

I have this same problem, I had FSX working for a few days, and, I'm not sure but I was Hibernating the PC, and I might have restarted it, and FSX worked fine; tonight I recieve this error "...was unable to load some system files and will now exit. Please reinstall flight simulator"...I restarted, problem persisted...I "Repaired" FSX problem persisted...I Uninstalled, restarted, installed FSX, Problem persisted...This has ruined my entire night, hopefully I can sort out a solution to this mess... and hopefully without having to reinstall!Any help is greatly appreciated!

I would be suspicious that you have some other program/dll loading because it has gotten into the path. I get this error when I run ATI Tray Tools and then run a program called 4NT. For some reason when ATI Tray Tools is running it's directory is now in the path of other programs that run. It has a dll called raphook.dll that causes 4NT and Take Command fits. If I close ATI Tray Tools then 4NT doesn't find ATT's raphook.dll and runs fine. With ATT open 4NT blows up.I found this out by using a tool called filemon. You can download it at http://sysinternals.com. There stuff is so good that Microsoft bought them. It's free so grab it while you can.Run it and then start FSX. Pay attention to the time that you get the error message (because filemon is going to capture a lot of information and the time will be your clue as to what happened right before it blew up).Filemon has the ability to filter (Options==>Filter/Highlight). You can put a list of wildcards in the "Exclude" section so that you don't see all the chatter of other programs that are running. You can also just include something like fsx.exe but then you don't know if FSX.exe runs something else that you would care about. So here is a sample Exclude filter that I use:filemon*;regmon*;svchost*;firefox*;winlogon*;explorer*;tcpview*;You would also want to include your anti-virus software if you have it running. Hope this helps.Bruce

Well I got FSX back up to operational status today after Using System Restore to Sunday (When I installed FSX) and after reinstalling the whole thing, it works again....Thanks for the reply though!